ADHESION OR ANTIADHESION IN CANCER - WHAT MATTERS MORE

The regulation of adhesion processes between normal epithelial cells i s an essential condition for the maintenance of appropriate tissular a rchitecture and differentiation. Quantitative and qualitative alterati ons in these homotypic adhesions occur during the transformation of no rmal into malignant epithelium. How these complex alterations in vario us homotypic adhesions modify the ability of tumor cells to detach fro m the original neoplastic site, to grow and move as single or clumped cells, and to invade the stroma are current issues in tumor biology. T his review contrasts tumor cell adhesion mediated by E-cadherin which is consistently decreased in carcinomas, with adhesion mediated by CD4 4 and CEA which are increased in the same tumors. A model proposing to resolve the apparent paradox of simultaneous adhesion and anti-adhesi on mediated by the same protein is proposed.